from tkinter import *

class Application(Frame):
    def __init__(this, master=None):
        super().__init__(master)
        this.pack()
        this.createWidgets()

    def createWidgets(this):
        this.label_0 = Label(this, text='Hello, world')
        this.label_0.pack()
        this.button_0 = Button(this, text='Quit', command=this.quit)
        this.button_0.pack()


app = Application()
app.master.title('Test GUI')
app.mainloop()
